Upgrade to sbt 1.9.9.

sjrd · sjrd · commit 734933aac38b · 2024-05-31T16:55:30.000+02:00
diff --git a/project/build.properties b/project/build.properties
@@ -1 +1 @@
-sbt.version=1.4.7
+sbt.version=1.9.9
